1. Field of the Invention
The present invention relates to an ignition coil for an internal combustion engine used to generate a spark within a combustion chamber of an engine, such as an internal combustion engine.
2. Description of the Related Art
In an internal combustion engine, an output portion of an ignition coil is disposed such as to be inserted into a plug hole provided in the engine. A spark plug is attached to an axial-direction tip end section of the output portion. The engine performs combustion as a result of ignition by the spark plug. Furthermore, in the internal combustion engine, to adjust the state of pressure within the plug hole depending on the expansion and contraction of air in accompaniment with temperature change, a ventilation passage is formed in the ignition coil.
As the engine cools from a heated state, the air within the plug hole cools. As a result, the pressure within the plug hole turns into negative pressure. If the ignition coil is exposed to water at this time, the water may infiltrate into the plug hole from the ventilation passage. Therefore, to prevent water infiltration, a sealing rubber or the like is disposed between the ignition coil and an opening section of the plug hole, and formation of the ventilation passage is modified.
As an ignition coil (ignition device) in which the ventilation passage has been modified, for example, an ignition coil disclosed in JP-A-2008-60188 is known. The ignition coil is configured such that a water collecting chamber and ventilation passage are formed in a side section of a connector case section disposed outside of the plug hole. The water collecting chamber is capable of collecting water that has infiltrated from outside of the connector case section. The ventilation passage communicates the water collecting chamber with the interior of the plug hole. Infiltration of water, such as cleaning water, into the plug hole can be prevented with certainty as a result of the water being collected in the water collecting chamber. The water collected in the water collecting chamber can be easily drained.
In addition, an ignition coil device for an internal combustion engine disclosed in JP-A-2007-303401 is configured such that a space is formed in an upper section within a connector case. A through-hole is formed downward from the space. The through-hole is communicated with the plug hole by a groove.
However, in JP-A-2008-60188, when water flows downward along a side wall section of the connector case section, the water may run around to a ventilation opening provided below the water collecting chamber and water infiltration may occur.
In addition, in JP-A-2007-303401, the space is formed by a cover that covers the connector case. Ventilation of the space is made possible by a gap formed between the cover and the connector case. Therefore, variations may occur in the formation of the gap. Although water infiltration may occur if the gap is increased, sufficient ventilation may not be possible if the gap is reduced.
Moreover, in JP-A-2008-60188 and JP-A-2007-303401, the cover is required to be separately fixed to the connector case section or the connector case by adhesion, welding, or the like. Therefore, production processes are numerous, and the inventions are insufficient for achieving reduction in production cost.